Re: [PATCH v8 21/24] KVM: riscv: selftests: Add SBI PMU selftest

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

On 4/20/24 8:17 PM, Atish Patra wrote:
> This test implements basic sanity test and cycle/instret event
> counting tests.
> 
> Reviewed-by: Anup Patel <anup@brainfault.org>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
LGTM

Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

> ---
>  tools/testing/selftests/kvm/Makefile          |   1 +
>  .../selftests/kvm/riscv/sbi_pmu_test.c        | 369 ++++++++++++++++++
>  2 files changed, 370 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 741c7dc16afc..1cfcd2797ee4 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -189,6 +189,7 @@ TEST_GEN_PROGS_s390x += rseq_test
>  TEST_GEN_PROGS_s390x += set_memory_region_test
>  TEST_GEN_PROGS_s390x += kvm_binary_stats_test
>  
> +TEST_GEN_PROGS_riscv += riscv/sbi_pmu_test
>  TEST_GEN_PROGS_riscv += arch_timer
>  TEST_GEN_PROGS_riscv += demand_paging_test
>  TEST_GEN_PROGS_riscv += dirty_log_test
> diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> new file mode 100644
> index 000000000000..7c81691e39c5
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> @@ -0,0 +1,369 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * sbi_pmu_test.c - Tests the riscv64 SBI PMU functionality.
> + *
> + * Copyright (c) 2024, Rivos Inc.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include "kvm_util.h"
> +#include "test_util.h"
> +#include "processor.h"
> +#include "sbi.h"
> +
> +/* Maximum counters(firmware + hardware) */
> +#define RISCV_MAX_PMU_COUNTERS 64
> +union sbi_pmu_ctr_info ctrinfo_arr[RISCV_MAX_PMU_COUNTERS];
> +
> +/* Cache the available counters in a bitmask */
> +static unsigned long counter_mask_available;
> +
> +static bool illegal_handler_invoked;
> +
> +unsigned long pmu_csr_read_num(int csr_num)
> +{
> +#define switchcase_csr_read(__csr_num, __val)		{\
> +	case __csr_num:					\
> +		__val = csr_read(__csr_num);		\
> +		break; }
> +#define switchcase_csr_read_2(__csr_num, __val)		{\
> +	switchcase_csr_read(__csr_num + 0, __val)	 \
> +	switchcase_csr_read(__csr_num + 1, __val)}
> +#define switchcase_csr_read_4(__csr_num, __val)		{\
> +	switchcase_csr_read_2(__csr_num + 0, __val)	 \
> +	switchcase_csr_read_2(__csr_num + 2, __val)}
> +#define switchcase_csr_read_8(__csr_num, __val)		{\
> +	switchcase_csr_read_4(__csr_num + 0, __val)	 \
> +	switchcase_csr_read_4(__csr_num + 4, __val)}
> +#define switchcase_csr_read_16(__csr_num, __val)	{\
> +	switchcase_csr_read_8(__csr_num + 0, __val)	 \
> +	switchcase_csr_read_8(__csr_num + 8, __val)}
> +#define switchcase_csr_read_32(__csr_num, __val)	{\
> +	switchcase_csr_read_16(__csr_num + 0, __val)	 \
> +	switchcase_csr_read_16(__csr_num + 16, __val)}
> +
> +	unsigned long ret = 0;
> +
> +	switch (csr_num) {
> +	switchcase_csr_read_32(CSR_CYCLE, ret)
> +	switchcase_csr_read_32(CSR_CYCLEH, ret)
> +	default :
> +		break;
> +	}
> +
> +	return ret;
> +#undef switchcase_csr_read_32
> +#undef switchcase_csr_read_16
> +#undef switchcase_csr_read_8
> +#undef switchcase_csr_read_4
> +#undef switchcase_csr_read_2
> +#undef switchcase_csr_read
> +}
> +
> +static inline void dummy_func_loop(uint64_t iter)
> +{
> +	int i = 0;
> +
> +	while (i < iter) {
> +		asm volatile("nop");
> +		i++;
> +	}
> +}
> +
> +static void start_counter(unsigned long counter, unsigned long start_flags,
> +			  unsigned long ival)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, counter, 1, start_flags,
> +			ival, 0, 0);
> +	__GUEST_ASSERT(ret.error == 0, "Unable to start counter %ld\n", counter);
> +}
> +
> +/* This should be invoked only for reset counter use case */
> +static void stop_reset_counter(unsigned long counter, unsigned long stop_flags)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, counter, 1,
> +					stop_flags | SBI_PMU_STOP_FLAG_RESET, 0, 0, 0);
> +	__GUEST_ASSERT(ret.error == SBI_ERR_ALREADY_STOPPED,
> +			       "Unable to stop counter %ld\n", counter);
> +}
> +
> +static void stop_counter(unsigned long counter, unsigned long stop_flags)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, counter, 1, stop_flags,
> +			0, 0, 0);
> +	__GUEST_ASSERT(ret.error == 0, "Unable to stop counter %ld error %ld\n",
> +			       counter, ret.error);
> +}
> +
> +static void guest_illegal_exception_handler(struct ex_regs *regs)
> +{
> +	__GUEST_ASSERT(regs->cause == EXC_INST_ILLEGAL,
> +		       "Unexpected exception handler %lx\n", regs->cause);
> +
> +	illegal_handler_invoked = true;
> +	/* skip the trapping instruction */
> +	regs->epc += 4;
> +}
> +
> +static unsigned long get_counter_index(unsigned long cbase, unsigned long cmask,
> +				       unsigned long cflags,
> +				       unsigned long event)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> +			cflags, event, 0, 0);
> +	__GUEST_ASSERT(ret.error == 0, "config matching failed %ld\n", ret.error);
> +	GUEST_ASSERT(ret.value < RISCV_MAX_PMU_COUNTERS);
> +	GUEST_ASSERT(BIT(ret.value) & counter_mask_available);
> +
> +	return ret.value;
> +}
> +
> +static unsigned long get_num_counters(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> +
> +	__GUEST_ASSERT(ret.error == 0, "Unable to retrieve number of counters from SBI PMU");
> +	__GUEST_ASSERT(ret.value < RISCV_MAX_PMU_COUNTERS,
> +		       "Invalid number of counters %ld\n", ret.value);
> +
> +	return ret.value;
> +}
> +
> +static void update_counter_info(int num_counters)
> +{
> +	int i = 0;
> +	struct sbiret ret;
> +
> +	for (i = 0; i < num_counters; i++) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> +
> +		/* There can be gaps in logical counter indicies*/
> +		if (ret.error)
> +			continue;
> +		GUEST_ASSERT_NE(ret.value, 0);
> +
> +		ctrinfo_arr[i].value = ret.value;
> +		counter_mask_available |= BIT(i);
> +	}
> +
> +	GUEST_ASSERT(counter_mask_available > 0);
> +}
> +
> +static unsigned long read_fw_counter(int idx, union sbi_pmu_ctr_info ctrinfo)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ, idx, 0, 0, 0, 0, 0);
> +	GUEST_ASSERT(ret.error == 0);
> +	return ret.value;
> +}
> +
> +static unsigned long read_counter(int idx, union sbi_pmu_ctr_info ctrinfo)
> +{
> +	unsigned long counter_val = 0;
> +
> +	__GUEST_ASSERT(ctrinfo.type < 2, "Invalid counter type %d", ctrinfo.type);
> +
> +	if (ctrinfo.type == SBI_PMU_CTR_TYPE_HW)
> +		counter_val = pmu_csr_read_num(ctrinfo.csr);
> +	else if (ctrinfo.type == SBI_PMU_CTR_TYPE_FW)
> +		counter_val = read_fw_counter(idx, ctrinfo);
> +
> +	return counter_val;
> +}
> +
> +static void test_pmu_event(unsigned long event)
> +{
> +	unsigned long counter;
> +	unsigned long counter_value_pre, counter_value_post;
> +	unsigned long counter_init_value = 100;
> +
> +	counter = get_counter_index(0, counter_mask_available, 0, event);
> +	counter_value_pre = read_counter(counter, ctrinfo_arr[counter]);
> +
> +	/* Do not set the initial value */
> +	start_counter(counter, 0, 0);
> +	dummy_func_loop(10000);
> +	stop_counter(counter, 0);
> +
> +	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
> +	__GUEST_ASSERT(counter_value_post > counter_value_pre,
> +		       "Event update verification failed: post [%lx] pre [%lx]\n",
> +		       counter_value_post, counter_value_pre);
> +
> +	/*
> +	 * We can't just update the counter without starting it.
> +	 * Do start/stop twice to simulate that by first initializing to a very
> +	 * high value and a low value after that.
> +	 */
> +	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, ULONG_MAX/2);
> +	stop_counter(counter, 0);
> +	counter_value_pre = read_counter(counter, ctrinfo_arr[counter]);
> +
> +	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, counter_init_value);
> +	stop_counter(counter, 0);
> +	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
> +	__GUEST_ASSERT(counter_value_pre > counter_value_post,
> +		       "Counter reinitialization verification failed : post [%lx] pre [%lx]\n",
> +		       counter_value_post, counter_value_pre);
> +
> +	/* Now set the initial value and compare */
> +	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, counter_init_value);
> +	dummy_func_loop(10000);
> +	stop_counter(counter, 0);
> +
> +	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
> +	__GUEST_ASSERT(counter_value_post > counter_init_value,
> +		       "Event update verification failed: post [%lx] pre [%lx]\n",
> +		       counter_value_post, counter_init_value);
> +
> +	stop_reset_counter(counter, 0);
> +}
> +
> +static void test_invalid_event(void)
> +{
> +	struct sbiret ret;
> +	unsigned long event = 0x1234; /* A random event */
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, 0,
> +			counter_mask_available, 0, event, 0, 0);
> +	GUEST_ASSERT_EQ(ret.error, SBI_ERR_NOT_SUPPORTED);
> +}
> +
> +static void test_pmu_events(void)
> +{
> +	int num_counters = 0;
> +
> +	/* Get the counter details */
> +	num_counters = get_num_counters();
> +	update_counter_info(num_counters);
> +
> +	/* Sanity testing for any random invalid event */
> +	test_invalid_event();
> +
> +	/* Only these two events are guaranteed to be present */
> +	test_pmu_event(SBI_PMU_HW_CPU_CYCLES);
> +	test_pmu_event(SBI_PMU_HW_INSTRUCTIONS);
> +
> +	GUEST_DONE();
> +}
> +
> +static void test_pmu_basic_sanity(void)
> +{
> +	long out_val = 0;
> +	bool probe;
> +	struct sbiret ret;
> +	int num_counters = 0, i;
> +	union sbi_pmu_ctr_info ctrinfo;
> +
> +	probe = guest_sbi_probe_extension(SBI_EXT_PMU, &out_val);
> +	GUEST_ASSERT(probe && out_val == 1);
> +
> +	num_counters = get_num_counters();
> +
> +	for (i = 0; i < num_counters; i++) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i,
> +				0, 0, 0, 0, 0);
> +
> +		/* There can be gaps in logical counter indicies*/
> +		if (ret.error)
> +			continue;
> +		GUEST_ASSERT_NE(ret.value, 0);
> +
> +		ctrinfo.value = ret.value;
> +
> +		/**
> +		 * Accessibility check of hardware and read capability of firmware counters.
> +		 * The spec doesn't mandate any initial value. No need to check any value.
> +		 */
> +		if (ctrinfo.type == SBI_PMU_CTR_TYPE_HW) {
> +			pmu_csr_read_num(ctrinfo.csr);
> +			GUEST_ASSERT(illegal_handler_invoked);
> +		} else if (ctrinfo.type == SBI_PMU_CTR_TYPE_FW) {
> +			read_fw_counter(i, ctrinfo);
> +		}
> +	}
> +
> +	GUEST_DONE();
> +}
> +
> +static void run_vcpu(struct kvm_vcpu *vcpu)
> +{
> +	struct ucall uc;
> +
> +	vcpu_run(vcpu);
> +	switch (get_ucall(vcpu, &uc)) {
> +	case UCALL_ABORT:
> +		REPORT_GUEST_ASSERT(uc);
> +		break;
> +	case UCALL_DONE:
> +	case UCALL_SYNC:
> +		break;
> +	default:
> +		TEST_FAIL("Unknown ucall %lu", uc.cmd);
> +		break;
> +	}
> +}
> +
> +void test_vm_destroy(struct kvm_vm *vm)
> +{
> +	memset(ctrinfo_arr, 0, sizeof(union sbi_pmu_ctr_info) * RISCV_MAX_PMU_COUNTERS);
> +	counter_mask_available = 0;
> +	kvm_vm_free(vm);
> +}
> +
> +static void test_vm_basic_test(void *guest_code)
> +{
> +	struct kvm_vm *vm;
> +	struct kvm_vcpu *vcpu;
> +
> +	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> +	__TEST_REQUIRE(__vcpu_has_sbi_ext(vcpu, KVM_RISCV_SBI_EXT_PMU),
> +				   "SBI PMU not available, skipping test");
> +	vm_init_vector_tables(vm);
> +	/* Illegal instruction handler is required to verify read access without configuration */
> +	vm_install_exception_handler(vm, EXC_INST_ILLEGAL, guest_illegal_exception_handler);
> +
> +	vcpu_init_vector_tables(vcpu);
> +	run_vcpu(vcpu);
> +
> +	test_vm_destroy(vm);
> +}
> +
> +static void test_vm_events_test(void *guest_code)
> +{
> +	struct kvm_vm *vm = NULL;
> +	struct kvm_vcpu *vcpu = NULL;
> +
> +	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> +	__TEST_REQUIRE(__vcpu_has_sbi_ext(vcpu, KVM_RISCV_SBI_EXT_PMU),
> +				   "SBI PMU not available, skipping test");
> +	run_vcpu(vcpu);
> +
> +	test_vm_destroy(vm);
> +}
> +
> +int main(void)
> +{
> +	test_vm_basic_test(test_pmu_basic_sanity);
> +	pr_info("SBI PMU basic test : PASS\n");
> +
> +	test_vm_events_test(test_pmu_events);
> +	pr_info("SBI PMU event verification test : PASS\n");
> +
> +	return 0;
> +}

-- 
BR,
Muhammad Usama Anjum